And I said private class fields were in the works. I’m happy to say that
private class fields have landed in Chrome 74. The new private fields syntax is
similar to public fields, except you mark the field as being private by using a
# (pound sign). Think of the # as being part of the field name.

CSS transition events

The CSS Transitions specification requires that
transition events are sent when a transition is enqueued,
starts, ends, or is canceled. These events have been supported in other
browsers for a while…

But, until now, they weren’t supported in Chrome. In Chrome 74 you can now
listen for:

transitionrun

transitionstart

transitionend

transitioncancel

By listening for these events, its possible to track or change behavior when a
transition is run.

Feature policy API updates

Feature policies, allow you to selectively enable, disable, and modify the
behavior of APIs and other web features. This is done either through the
Feature-Policy header or through the allow attribute on an iframe.

HTTP Header:Feature-Policy: geolocation 'self'

<iframe ... allow="geolocation self">
</iframe>

Chrome 74 introduces a new set of APIs to check which features are enabled:

You can get a list of features allowed with
document.featurePolicy.allowedFeatures().

You can check if a specific feature is allowed with
document.featurePolicy.allowsFeature(...).

And, you can get a list of domains used on the current page that allow a
specified feature with document.featurePolicy.getAllowlistForFeature().

And more!

These are just a few of the changes in Chrome 74 for developers, of course,
there’s plenty more. Personally, I’m pretty excited about
KV Storage, a super fast, async,
key/value storage service, available as an origin trial.

Google I/O is happening soon!

And don’t forget - Google I/O is just a few
weeks away (May 7th to 9th) and we’ll have lots of great new stuff for you.
If you can't make it, all of the sessions will be live streamed, and will be
available on our
Chrome Developers YouTube channel
afterwards.